Complimentary Metal Oxide Semiconductor (CMOS) image sensors typically include a photodiode and a Metal Oxide Semiconductor (MOS) transistor in each unit pixel. CMOS image sensors sequentially detect electric signals of each unit pixel in a switching mode to realize images.
A CMOS image sensor includes a photodiode area for receiving an optical signal and converting it into an electrical signal and a transistor area for processing the electrical signal.
A typical related art CMOS image sensor has a structure in which the photodiode and the transistor are horizontally arranged on the semiconductor substrate. Thus, much of the incident light does not strike the photodiode, leading to a low fill factor.
Thus, there exists a need in the art for an improved image sensor and manufacturing method thereof.